Electric control apparatus



Jan- 14, 1936- J. osTERME-IER Er AL 2,027,399

ELECTRIC CONTROL APPARATUS Filed Dec. l0, 1931 Patented Jan. 14, 1936 UNITED STATES PATENT OFFICE ELECTRIC CONTROL APPARATUS Johannes Ostermeier, Mering, and Johann Michel, Augsburg, Germany 7 Claims.

Our invention relates to electric control apparatus of the type in which the current in an electric circuit is varied by varying the distance of a conductor from the circuit and such variation is utilized for influencing an appliance in the circuit which may be the apparatus to be controlled, such as a signalling, indicating, alarm, registering, advertising, or any other apparatus. or a relay for operating the apparatus.

It is an object of our invention to provide a lo control apparatus of the type set out above which is simple, very sensitive to variations in the distance of the conductor, exactly adjustable, of constant and strong effect, and not influenced by moderate variations in the voltage of the circuit.

To this end we provide a source of voltage in electric connection to the appliance to be controlled, and a gas discharge or glow discharge tube which undergoes a variation of its discharge if the distance of a body outside the tube from the tube is varied.

In the accompanying drawing three types of apparatus embodying our invention are illusf trated diagrammatically by way of example.

In the drawing Fig. 1 is a diagram of the simplest type,

Fig. 2 is a diagram of an apparatus with a screen, and

Fig. 3 is a diagram of an apparatus with a screen, a heated cathode, and an intermediate conductor.

Referring now to the drawing, 2 is the secondary winding of a transformer which is connected to an alternating-current system, not shown, l u is its primary winding which is shown only in Fig. 1, 3 is a cathode in a gas-discharge tube I8, E is the anode, also in the tube I6, and 6 is a surface conductor which must be perfectly insulated and is here shown as a metal layer in 40 the tube. The cathode 3 is connected to one end of the secondary 2, and the wire connecting it to the secondary is grounded at I0. The anode 5 is connected to the'other end of the secondary, and in the connecting wire is provided a relay 5 4, Fig. 1, or an indicating apparatus of any suitable type, 4', Figs. 2 and 3, 1 is a grounded conductor the distance of which from tube I6 may be varied as indicated by the double-pointed arrow. n If the conductor 1 is at a given distance from the tube I6 there will be no discharge in the tube and the relay 4, or the indicating apparatus 4', as the case may be, is not excited. If the conductor 1 moves nearer to the tube I6 a. disu charge will occur and the relay will be excited and (Cl. Z50-27) operate the apparatus connected to it, or, in the case of Figs. 2 and 3, the apparatus 4' itself will be operated.

The conductor 1 may be grounded or not. Its potential may be equal, or substantially equal, to that of one of the electrodes, preferably the cathode 3, in the tube i6. For instance, the cathode or the terminal of the supply of current may be grounded and the conductor 1 may also be grounded, as shown in Fig. 1.

Under certain conditions the eifect is improvedv if the potential of conductor 1 is different from that of both electrodes 3 and 5. Or one of the electrodes, say the cathode 3, may be grounded and the conductor 1 may be insulated from ground, or, conversely, the circuit of the tube I6 may be insulated from ground, and the conductor 1 grounded.

As described the discharge in the tube I6 begins when the distance of the conductor 1 undero steps a certain limit. However, the disposition may be modified so that the discharge ceases when the conductor moves nearer to the tube, and is .restarted when it moves further away. By varying the distance of the conductor from the 5 tube, the current in the tube circuit may be varied also.

The movable conductor 1 may be carried by a person or by a vehicle, or may be the person or the vehicle itself. It is not necessary that the conductor should be movable and the tube fixed, but the tube and its system may be movable with respect to a fixed conductor, or both may be movable with respect to each other.

The surface conductor 6 is preferably provid- 35 ed as it improves the effect. It may be a metal layer on the inner wall of the tube I6 and need not be connected to its electrodes 3 and 5.

Referring to Fig. 2, the parts are arranged substantially as described with reference to Fig. 40 1 but here the ground l0 is not connected to one end of the secondary 2 but to a point between its ends, and the lower portion of the secondary is equipped with a contact slide 9 connected to a screen 8. The screen 8 is so arranged that 45 the discharge which would normally occur, is suppressed by it but is released when the conductor 1 moves nearer to the tube I6, and ceases when it is moved further away from it. By reversing the polarity of the portion of secondary 2 which supplies the screen 8 with current, the system may be modified so that the screen *l brings about the discharge which would not occur were the screen not present, the discharge ceasing when the conductor moves nearer to the tube II, and restarting when it moves further away.

If desired the conductor 'I may be arranged between the screen l and the tube Il.

'Ihe potential of the screen l which is resti-- lated by the slide 9, has the same periodicity as the anode I. By suitably selecting the position and the form of the screen l-which need not be an arched plate as shown but might, for instance, be a wire wound about the tube Il-the sensitivity of the apparatus to variations in the voltage of the source of current, and its inertia may be reduced. Inertia here stands for the difference between the two distances of the movable conductor 'i at which discharge begins or, in the opposite direction of movement of the conductor, ceases. Sensitivity is the distance of the conductor 'i and the tube at which the discharge starts. This sensitivity varies very much with the anode voltage, because the small diiference between the constant ignition voltage and the anode voltage, on the amount of which the effect is based, varies very much-for a small percentage of variation in the anode voltage. Variation of the screen potential at constant anode potential also influences the sensitivity, but in the opposite direction, and as in the arrangement of Fig. 2 the anode and screen potentials vary together the two influences balance each other. This effects a great constancy of the apparatus.

The potential of the screen or auxiliary conductor 8 may be dephased or opposite to the potential of the anode 5 of the tube it, as shown in F18. 2.

Another advantage of the screen or auxiliary conductor l is the very fine regulation by slide 8 or any other suitable means.

Referring now to Fig. 3, the cathode 3- is a filment and supplied with current from two taps Il and I2 at the secondary 7. By these means the intensity of the discharge current is increased, as is known in the art. The ground Il is connected to the secondary 2 between the tappings il and l2.

i3 "is an intermediate conductor between the movable conductor 1 and the tube it. i4 is an outer electrode and I5 is a wire connecting the conductor Il to the outer electrode. The outer electrode Il must be within'the range of the tube but the intermediate conductor I3 andthe movable conductor 1 may be at any distance from the tube. as the intermediate conductor il v is not bound to the immediate vicinity of the tube.

As mentioned, we are not limited to a fixed tube il and a movable conductor 1 but the conductor may be fixed and the tube movable, or both may be movable with respect to each other.

Our invention may also be modiiied in various other -ways without departing from the gist thereof.

It has a very wide range of usefulness. Signalling etc. have already been mentioned. Other possibilities are its application tofsafety devices against unauthorized persons, whose approach is indicated by the apparatus, or for warning persons that they must not enter a certain room or the like because it is dangerous. For railways, it may be used for registering trains passing a given point, or for signalling the approach of a train toward a station or level crossing. It may also be used for operating automatic devices, for instance a door-opener, a cigarlighter etc., which become active as a person approaches.

We claim:

1. An electric control system comprising a gas discharge tube, a source of voltage arranged to produce a discharge current between electrodes within said tube, a conductor outside said tube `and forming with at least one internal electrode thereof -a loose capacity coupling with a large stray field, a source of voltage arranged to maintain the field of said capacity coupling and by means of said internal electrode controlling the discharge current in the tube, and means for indicating discharge current variations due to disturbance'of the field.

2. An electric control system according to claim 1 comprising also means for adjusting the potential applied between the electrodes of the loose capacity coupling.

3. A system according to claim 1 in which the source of voltage is an alternating source.

4. An electric control systemcomprising a gas discharge tube, a source of alternating voltage arranged to produce a discharge between electrodes within said tube, a conductor outside said tube and forming with at least one intemai electrode thereof a loose capacity coupling with a large stray field, a source of alternating voltage for producing the field of said capacity coupling, this voltage being about 180 out of phase with respect to the voltage of the first mentioned alternating source and by means of said internal electrode controlling the discharge in the tube, and means responsive to discharge current through the tube.

5. A system according to claim 4 in which one oi the electrodes of the tube is a thermionic electrode.

6. An electric control system comprising a gas discharge tube with a plurality of internal electrodes including an anodeand a cathode, a source of voltage connected to the anode and cathode.

means responsive to discharge current through..

the tube, a conductor external to the tube cooperating with an internal electrode thereof to form therewith a loose capacity coupling, and connections i'or applying potential to said capacity coupling, to control the passage of discharge cur- 

